


The Color of My Heart

by Katsnap



Category: Undertale (Video Game)
Genre: Alternate Universe - Underswap (Undertale), F/M, Protective Papyrus, Reader-Insert, Underswap Papyrus, Underswap Sans, sans x reader
Language: English
Status: In-Progress
Published: 2018-08-01
Updated: 2018-12-19
Packaged: 2019-06-20 00:26:13
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 3,315
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15522039
Author URL: https://archiveofourown.org/users/Katsnap/pseuds/Katsnap
Summary: Thrown into the world of monsters as a baby, (Y/n) is raised as Asgore's own child, kept sheltered in the Ruins until she's old enough to travel through the Underground with relative safety. Not expecting to absolutely love the little town of Snowdin, it was inevitable that she ends up meeting the Skele-Brothers. While excitable Blue is more than happy to be her friend, his brother isn't quite as welcoming.Even less so when those feelings of friendship grow to something more.The added oppression of something going horribly wrong with the timeline isn't helping any.





	1. Prologue

            She was barely a few days old when she was thrown down the hole in that mountain cavern. Tossed away like trash by a mother who considered her a mistake she hadn’t caught in time. The child would disappear, and she’d never have to deal with her again. She didn’t even stick around to see if her plan had worked—she walked off as soon as her terrible deed had been done.

            Instead of killing the baby, like the woman had hoped, the infant landed on a bed of flowers. Her landing was cushioned, and her blanket swaddle kept her quite safe. It was close to an hour, though, before a curious figure approached to investigate her screaming and wailing. The large figure peered around a ruined column and gasped in shock.

            “Oh my Stars! What…what kind of horrible being would…?” He glanced up at the hole, now only a pinpoint of light above him, with abject horror. Truly, whomever was responsible for such a thing was far worse a monster than any that lived down here with him. He approached the child and crouched to carefully gather the newborn into his arms, cradling her close to his broad chest.

            “Hush now, little one. You’re safe now,” he softly cooed to the baby, swaying a little to soothe the poor dear. She slowly started to quiet down to soft whimpers and snubs, and he gently stroked a chubby cheek with a clawed hand very gently. “Dear me….I’m not even sure _how_ to raise a human child….but I suppose we’ll have to learn together, my dear.”

            The large goat monster stood and turned to head back to his home, carrying the infant close to his chest as he walked. “I suppose the first step would be to find you something to eat. I may have to contact a good friend of mine for some help…Oh! I suppose you need a name, don’t you? Goodness, I’ve never been very good at naming….how about….how about (Y/n)? Yes…yes, that’s a very good name, I think. You will be called (Y/n) from now on.”

            Despite being a completely different species, (Y/n) was still raised and loved by Asgore like he would have if she had been his child by blood. (Y/n) became aware at a young age that she was not a monster like Asgore, but that didn’t matter much to her. She still loved her adoptive father with all her heart.

            (Y/n) rarely left the Ruins, as Asgore deemed it too dangerous for her to leave his side as she grew up. She was generally quite happy to stay close by or to play in the field of flowers she had been found in. She spent much of her childhood talking to the flowers or singing sweet songs to them, her young voice echoing throughout the vast cavern her home was in.

            As she grew older, Asgore began to teach her about magic and SOULS. He taught her how to protect herself if ever she would need to, how to FIGHT back if the situation called for it. He prayed she would never need to use her magic for battles though, and he doubted she would ever harm another being—she was too tenderhearted and too kind to hurt someone else, and she hated confrontation.

So, she decided at a young age to only ever use her magic to help.


	2. Chapter One

**Notes for the Chapter:**

> Alright guys, don't judge too harshly. I'm kind of new to the Undertale fandom, and Underswap is one of my favorite AUs.

            (Y/n) was sixteen years old when she left the ruins for the first time. She was curious about the rest of the Underground, and Asgore agreed that she needed to start interacting with other monsters and learning about where she lived. At the time, it was just a quick exploration through Waterfall, just past Snowdin, and it was with Asgore by her side. But (Y/n) loved the Echo Flowers and the gentle sound of rain and running water. She promised herself that she’d return to Waterfall again after she explored all of the Underground.

            They returned to the Ruins and made small trips outside of them to meet some of Asgore’s old friends, but otherwise, (Y/n) didn’t stray far from her home. She didn’t truly leave the Ruins until she was twenty-four. By then, Asgore felt her magic was strong enough to protect her and she was capable of handling other monsters that would be less than friendly towards her. She hated leaving her father behind, but she also knew she couldn’t stay there forever. She wanted to make a living for herself and travel the Underground.

            Her plan of action would be to travel to Snowdin first, stay for a little while, get used to the locale before moving on to the next section. She wasn’t expecting to completely fall in love with the lovely little town though, and before she knew it, she was settling down at the inn with a fantastic agreement with the owner. She’d work as a maid a few days a week and her stay would be free. They’d even pay her a small amount for doing an excellent job!

            (Y/n) made friends quickly, and she loved exploring all the little shops and restaurants. Her favorite was a bakery run by a spider monster named Muffet. She loved the baked goods and the hot chocolate was to die for. She often visited when she had a craving for something sweet. The monsters she had met didn’t seem to mind that she was a human—in fact, they seemed quite amazed that a human could be so kind.

            From sitting and listening in to various conversations, she heard of a pair of skeleton brothers that often worked as patrol and watch for all of Snowdin—apparently, the youngest was striving to join the Royal Guard and his brother was just kind of…there to support him. She hadn’t seen either of them yet, though, having been busy a lot of the time with her job as a maid.

            In fact, her very first encounter with one of the brothers was while she was sitting in Muffet’s for a cup of hot chocolate and one of Muffet’s famous spider cookies. She had just come in from outside, so she still wore her heavy hooded jacket and scarf to keep out the cold. Snowdin could get quite cold sometimes.

            She had just received her drink and cookie and tugged down her scarf, so that she could sip at the hot beverage. It warmed her up nicely and she sighed in contentment, pushing her hood back so it didn’t get in the way. A sudden, thrilled squeak beside her made her jump and look over in surprise. Practically vibrating in excitement was a skeleton monster, about five or so inches shorter than her. He wore a bright blue scarf and a grayish color chest plate with matching pauldrons. His eye orbitals were wide and his eyelights were big and bright blue, shining in his joy. He pointed a gloved finger at her.

            “YOU! YOU’RE A HUMAN!!” He exclaimed.

            “Um…yes?” (Y/n) blinked in confusion at his excitement, before she remembered that most, if not all monsters had never seen a human before. So…she could kinda understand his enthusiasm. “And you’re a skeleton.”

            “THAT I AM, HUMAN! MWEHEHEH! I AM SANS, THE MAGNIFICENT!” He introduced himself with great flourishment, and (Y/n) grinned a little. “ALTHOUGH, EVERYONE CALLS ME BLUEBERRY. I’M NOT SURE WHY.”

            (Y/n) couldn’t help herself. She giggled a little. He was really quite cute for a skeleton monster—how on earth did a skeleton have such a round, squishy, and expressive face?

            “Well, it’s a pleasure to meet you, Sans the Magnificent. My name is (Y/n) Dreemur,” she smiled and held out a hand to shake. The skeleton took it gleefully and gave a firm, enthusiastic shake.

            “IT MOST CERTAINLY IS A PLEASURE! AND TO MEET A HUMAN WITH SUCH WONDERFUL MANNERS AT THAT!”

            “Awe! Thank you!” Stars, he was adorable. She really had to fight the urge to just hug him. “Heh…I think I know why they call you Blueberry.”

            “OH? DO TELL!”

            “It’s because you’re so sweet and cute!”

            The skeleton looked quite startled by this declaration and his cheeks flushed a bright blue. “I-I am?” He squeaked.

            “Oh, yes indeed!” She chuckled at the change of volume. Oh. My. Stars. That blush just about did it in for her. She wasn’t going to be able to contain her squeal for much longer. She bit back a giggle for his sake and decided to change the subject. “So, are you the only skeleton around here?”

            Blue seemed quite glad for the change of topic and quickly answered her question. “OH, NOT AT ALL! MY ELDER BROTHER LIVES HERE AS WELL! OF COURSE, HE’S A SACK OF LAZY BONES WHO DOESN’T PUT MUCH EFFORT INTO….WELL, ANYTHING. SO, THE CHANCES OF YOU RUNNING INTO HIM OUTSIDE OF OUR HOME IS VERY SLIM.”

            (Y/n) couldn’t help herself—she burst out laughing. Blue looked quite pleased that he made her laugh and he cheeks darkened once again. “A sack of lazy bones, huh? Maybe you can introduce me to him some time.”

            “YES, PERHAPS SO!”

            (Y/n) ended up wasting a good hour just sitting and chatting with Blue. She probably also gained a good ten pounds just from eating Muffet’s baked goods while she sat there. Luckily, Muffet was kind enough to give her a discount for being a regular customer so she didn’t spend too much money. She actually ended up agreeing to meet Blue there tomorrow for lunch, having enjoyed his company as much as she did.

            Blue was an excitable, talkative monster that delighted her with his vast knowledge in various subjects. If it was something he was passionate about, he would wiggle in his seat and his eye sockets would widen. When she talked about something she enjoyed, he would watch her with great interest, eyelights watching her expressions and body language. Even Muffet would stop by to listen to the conversation, watching with a knowing smile at the pair.

            It was the start of something beautiful.


	3. Chapter Two

**Notes for the Chapter:**

> >_< Omigoodness, you guys are so amazing! <3 I've been getting such wonderful comments about this fic! Thank you!!!  
> This is a short chapter, but it gets the job done. :)

            (Y/n) had become fast friends with Blue, spending much of her free time with the excitable skeleton. She often times joined him on his patrols around Snowdin, and even met his mentor Alphys (a slightly terrifying lizard monster). She met everyone that Blue knew and even made a few new friends from it all. It was only afterwards that Blue decided she should meet his brother.

            (Y/n) was more than happy to do so—she enjoyed hanging out with the cute skeleton, and besides, someone related to such a sweet monster had to be just as nice, right?

            Sometimes, reality truly left a sour taste in her mouth. Meeting Stretch had been….well, less than pleasant.

            Entering the two-story house, (Y/n) was welcomed by a warm and cozy home that was well loved and well lived in. It was clean, but quite obvious two different personalities lived there. Blue shouted up the stairs for his brother as (Y/n) shrugged off her coat, smiling a little as she looked around. Goodness, she wouldn’t mind living in a house like this.

            Slow, dragging footsteps drew her attention to the stairs, and down came a tall, thin skeleton wearing an orange, rather faded looking hoody and cargo shorts, bony feet stuffed into unlaced converses. His pace slowed even more as his gaze locked onto her form and his expression changed from something lazy and content to something…judgmental.

            It wasn’t often (Y/n) felt uneasy, but there was a wariness that came with Stretch’s appearance. He looked just as lazy and unmotivated as Blue claimed, but there was a rolling power that she sensed that would probably have given Asgore a run for his money. There was nothing comforting about it, either.

            Still, she smiled warmly and walked over to stand beside Blue, holding her hand out to shake. “Hello. My name’s (Y/n). You’re Stretch, right?” She greeted him kindly, praying he’d relax once he realized she was a friend. Instead, he barely glanced at her hand and his eyes narrowed a little.

            He looked her straight in the eye and his voice drawled out a very clear warning.

            “I don’t like you being around my brother. I’m watching you closely, human.”

            (Y/n) was…stunned, for lack of a better word. He strolled into the kitchen, leaving her gaping after him, hand hanging loosely in the air. Even Blue’s sweet, excited smile had faded as his brother moseyed off. She left her hand drift back to her side, absently picking at a spot on her pants as feelings of confusion and dejectedness rolled through her. She didn’t understand—every monster she had met so far had been friendly and cheerful, more than happy to be her friend. Even Alphys had been nice enough, even if she was a little scary and rough.

            “….I…don’t think you brother likes me very much…” (Y/n) said quietly, frowning.

            “IT’S NOTHING PERSONAL. HE DOESN’T LIKE MEETING NEW PEOPLE. I’M SURE HE’LL WARM UP TO YOU!” Blue didn’t really look very convinced himself, but he was trying. He reached out and took her hand, giving a gentle squeeze and smiled at her, before shifting topics towards her see his newest puzzle. It definitely worked as a distraction and she ended up enjoying her visit more than she first thought. Unpleasant encounter aside, she did like being able to visit Blue at home.

            When she left that evening to head back to the inn, she felt an uncomfortable gaze follow her, until the house was out of sight and she was trudging through fresh snow that had fallen. She really did hope Blue was right, and that Stretch would eventually warm up to her. She truly did want to be his friend, and she was sure he could be a wonderful person if he would relax around her.

            _Just a little time,_ she thought as she climbed into bed that night. _Just give it a little time. Blue’s right. He’ll come around._


	4. Chapter Three

**Notes for the Chapter:**

> Holy CROW, I LIVE!
> 
> I am so sorry, my sweets! I have been bombarded this past year, and it's kicked me into a huge rut with my writing.
> 
> But I come with a peace offering!
> 
> A new chapter!!
> 
> Enjoy~

            (Y/n) gave Stretch time to get used to her, yet Stretch’s distaste for her didn’t end after a few days, or even after a few weeks. Anytime she visited Blue at home, Stretch was always there to keep an eye on her. Always with a cold gaze that never failed to make her feel uncomfortable.

            It bewildered her, to be honest, since she had seen him interacting with other monsters. He was generally pretty content and tended to make a lot of puns and jokes, chatting with the locals a lot. She was the only one he treated so aloofly. It kind of hurt, really.

            Especially considering how much (Y/n) was finding herself liking Blue. She liked Blue _a lot_. Well past friends and moving into potential relationship territory. She really did want Stretch to like her, even just a little, and more than once she tried to become friends with him. She spent hours trying to talk and joke with him, even slipping a few puns in (much to Blue’s extreme disgust).

            Nothing seemed to work. He just glowered, stared or flat our ignored her until she trailed off in disappointed silence.

            What made it worse was the fact Blue noticed his brother’s behavior. And he wasn’t too happy with it. Blue liked (Y/n) a lot, would probably even admit that he was falling in love with the human girl. She was a kind and happy individual, and she enjoyed making others smile and laugh. She was well liked by most everyone in Snowdin.

            Stretch was the only one that did not. Why, Blue couldn’t figure out. He knew he hated seeing her expression when Stretch blew her off and shot an unkind comment at her. He knew she always looked so sad and hurt, and it made his soul hurt seeing her try not to cry. So he tried twice as hard to make her happy again.

            Blue often went on patrols with her or they hung out at Grillby’s, so she wasn’t around his brother as much. Sometimes they just hung out at the room she rented at the inn and messed with whatever puzzle or game he brought over. Or they just talked.   

            “Say, Blue, is your brother….is he a little overprotective?” (Y/n) asked randomly one evening while helping the smaller skeleton with a puzzle. Blue didn’t look up as he carefully slid a piece into place.

            “….yes, I suppose that’s one way to put it,” he finally sighed. His normally loud voice was often subdued when he was concentrating on something, as he said his great voice would distract him if he used it all the time. “Papyrus has always had my best interests in mind, but….he does perhaps go a little too far at times. Such as the situation with you.”

            (Y/n) grimaced a little. She had hoped Blue wouldn’t have noticed it too much, but it seemed the hyper monster was far more observant than she first believed. “Yes, well….i-in what other ways has he gone too far?”

            Blue finally lifted his gaze up to look at her for a moment, his bright eyelights unnervingly perceptive. “I think he forgets at times that I’m not a child anymore. I understand that at times I act far younger than I really am, so that probably doesn’t help any, but I am still an adult.”

            (Y/n) gave a weak smile, handing him another piece. “You do act rather childish at times. But it’s cute.”

            His cheeks turned a light blue and his fingers fumbled with the puzzle piece.

            “But you do show your adult side more often than not. Maybe it’s just…because he’s your big brother?” (Y/n) shrugged a little. “I mean, he probably still sees you as just his little brother—not another fully grown adult.”

            Blue drummed his fingers for a moment, eyes back down at the puzzle. “Yes, I suppose so….”

            “Unfortunately, this….thing that’s going on between me and your brother…I-I really don’t know how to address it. I mean,” (Y/n) sighed and leaned back in the beanbag that made up her chair. “I’ve _tried_ talking to him, but he either just…shoots me dirty looks until I stop talking or walks off while I’m mid-sentence. The biggest thing I can’t understand is…well, I’ve done nothing wrong, have I?”

            She let a bit of uncertainty and self-doubt enter her voice unbiddenly and Blue looked up quickly once again. A frown pulled at his mouth and marred his normally sweet expression. “My brother is….he’s far more complicated than he lets other believe. But…no, you’ve done nothing wrong, (Y/n).”

            He reached out and laid his hand on top of her, gently squeezing in comfort. (Y/n) absently noted the worn fabric along the pads of his fingertips and the palm of his hand. He must have had these gloves for many years. Maybe she should get him new ones for his birthday.

            “Don’t let what my brother does change how you act around us, okay?” he said gently. Her eyes met his for a moment. She relaxed a little and gave a soft smile.

            “Yeah. Of course.”

            Blue’s smile returned, and he gave another hand squeeze before he returned back to his puzzle. It was quiet for several long minutes before (Y/n) grinned a little mischievously.

            “Still cute though, even when you act as an adult.”

            She’d never seen Blue blush so deeply, so quickly before and she broke into laughter as he whined and threw a pillow at her to get her to stop flustering him.


End file.
